Re: apt debug

[Greg Wooledge <greg@wooledge.org>]

On Mon, Oct 13, 2025 at 13:07:37 +0000, fxkl47BF@protonmail.com wrote:
> On Mon, 13 Oct 2025, Greg Wooledge wrote:
> 
> > On Mon, Oct 13, 2025 at 12:43:13 +0000, fxkl47BF@protonmail.com wrote:
> >> apt list ~e^science
> >>
> >> how can i see the details of what is being searched and how
> >
> > man apt-patterns
> >
> >       ?source-package(REGEX), ~eREGEX
> >           Selects versions where the source package name matches the specified
> >           regular expression.
> >
> > man 7 regex
> >
> >       '^'  (matching the null string at the beginning of a line)
> >
> 
> 
> i've read that several times
> i don't see anything that tells me the details of how apt is performing the search

I don't understand what you're asking.

~e means the rest of it is a regex (regular expression) which is matched
against the source package name.  (It would be nice if it specified
which flavor of regex it's using, because there are many.)

^science is a regex that matches any string/line beginning with the
substring "science".  (At least in BRE, ERE and PCRE flavors.)

So, putting it together, it should match all packages whose source package
name begins with "science".

When I run it on my system, I get the following result:

hobbit:~$ apt list '~e^science'
ESC[32mlibjs-sciencejsESC[0m/stable,stable 1.9.3+dfsg-4 all

This package is not installed, so it seems it's looking at available
packages.  This is the package it's referring to:

hobbit:~$ apt-cache show libjs-sciencejs
Package: libjs-sciencejs
Source: science.js
Version: 1.9.3+dfsg-4
[...]

As you can see, its source package name is "science.js" which does in
fact begin with "science".  So, it looks like it's working as documented.